(1) Field of the Invention
The present invention relates to a liquid crystal display device and a manufacturing method for the same, and in particular, to a longitudinal electrical field mode liquid crystal display device, and a manufacturing method for the same.
(2) Description of the Related Art
Liquid crystal display devices (panels) have a pair of substrates that are positioned so as to face each other and sandwich liquid crystal as outer walls.
In addition, liquid crystal display devices of a so-called longitudinal electrical field mode are provided with a number of pixel electrodes that are positioned in a matrix which are supplied with independent video signals on the surface of one substrate (first substrate) on the liquid crystal side, and a counter electrode that is formed so as to be shared by pixels to which a reference signal for the video signals is supplied on the surface of the other substrate (second substrate) on the liquid crystal side.
The pixel electrodes and the counter electrode are usually formed of a transparent conductive film, so that liquid crystal molecules can be driven by electrical fields in accordance with the difference in potential between the respective pixel electrodes and the counter electrode. In this case, the electrical fields generated between the pixel electrodes and the counter electrode are approximately perpendicular to the substrates (longitudinal), and this is why such liquid crystal display devices are said to have a longitudinal electrical field mode.
In addition, the counter electrode has protrusions (hereinafter referred to as pad portions) in the direction of a diagonal line in a corner, for example, and the structure allows the counter electrode to electrically lead out onto the first substrate through a conductive material provided between the first substrate and second substrate that makes contact with the pad portions. Thus, the terminals for supplying a signal to the counter electrode can be provided in parallel with the terminals for supplying signals in order to drive the pixel electrodes.
FIG. 7A to FIG. 7C are plan diagrams showing an example of the counter electrode CT formed in the second substrate SUB2. Here, FIG. 7A to FIG. 7C correspond to FIG. 5A to FIG. 5C, which show an embodiment of the present invention. Therefore, FIG. 5A to FIG. 5C and other drawings relating to these figures should be referred to for structures that are not described below. In FIG. 7A, the counter electrode CT is provided with pad portions PD (denoted by symbols PD1 and PD2 in the figure) which protrude in the direction in which the below described alignment film ORI2 is rubbed (direction of arrow A in the figure; 45° relative to side of second substrate SUB2) in the corners. FIG. 7B is a diagram showing an enlargement of the pad portion PD1, and FIG. 7B is a diagram showing an enlargement of the pad portion PD2. In this case, the two sides of either the pad portion PD1 or PD2 extend in the direction in which the pad portion protrudes from the counter electrode CT at an angle of 45° relative to the side of the second substrate SUB2 that crosses the extended line of the two sides of the pad. In addition, FIG. 8A to FIG. 8C are diagrams showing another example of the counter electrode CT formed on the second substrate SUB2 and correspond to FIG. 7A to FIG. 7C. The pad portions PD′ in FIG. 8A to FIG. 8C (denoted by PD1′ and PD2′ in the figures) have two sides which extend in the direction in which the pad protrudes from the counter electrode CT at an angle of 90° relative to the side of the second substrate SUB2 that crosses the extended line of the two sides of the pad.
The pad portions PD of the counter electrode CT in FIG. 7A to FIG. 7C are disclosed in JP1996-234220A, and the pad portion PD1′ of the counter electrode CT in FIG. 8A to FIG. 8C is disclosed in JP1995-270825A.
In addition, documents relating to the present invention include JP2005-227582A and JP2004-212690A. JP2005-227582A describes that the amount of streaks left when the alignment film is rubbed can be reduced by not forming protruding pad portions in the counter electrode, as described above. Thus, the invention is different from the present invention, which is based on the formation of protruding pad portions in the counter electrode. In JP2004-212690A, one of the two sides along the protruding pad portions of the counter electrode runs 90° relative to the sides of the counter electrode, while the other runs at a smaller angle. However, there are no descriptions concerning the direction in which the alignment is rubbed, and its relation to the pattern of the pad portions is not clear.
Here, in some cases a resin film is formed in a predetermined region on the counter electrode CT after the counter electrodes CT is formed on the substrate SUB2, and then rubbed using a rubbing roller, so that an alignment film ORI2 is formed. As shown in FIG. 7A, in the case of the counter electrode CT shown in FIG. 7A to FIG. 7C, when the resin film is rubbed at an angle of 45° relative to the sides of the substrate SUB2, as described above, so-called rubbing streaks RLN1 and RLN2 are left on the surface of the alignment film ORI2 in the vicinity of the pad portions PD.